﻿// Copyright 2004-2011 Castle Project - http://www.castleproject.org/
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#region 导入名称空间

using System;
using System.Reflection;
using System.Reflection.Emit;

#endregion

namespace LightWork.DynamicProxy.Generators.Emitters.SimpleAST
{
    public class BindDelegateExpression : Expression
    {
        private readonly ConstructorInfo delegateCtor;
        private readonly MethodInfo methodToBindTo;
        private readonly Expression owner;

        public BindDelegateExpression(Type @delegate, Expression owner, MethodInfo methodToBindTo,
            GenericTypeParameterBuilder[] genericTypeParams)
        {
            delegateCtor = @delegate.GetConstructors()[0];
            this.methodToBindTo = methodToBindTo;
            if (@delegate.IsGenericTypeDefinition)
            {
                var closedDelegate = @delegate.MakeGenericType(genericTypeParams);
                delegateCtor = TypeBuilder.GetConstructor(closedDelegate, delegateCtor);
                this.methodToBindTo = methodToBindTo.MakeGenericMethod(genericTypeParams);
            }
            this.owner = owner;
        }

        public override void Emit(IMemberEmitter member, ILGenerator gen)
        {
            owner.Emit(member, gen);
            gen.Emit(OpCodes.Dup);
            if (methodToBindTo.IsFinal)
                gen.Emit(OpCodes.Ldftn, methodToBindTo);
            else
                gen.Emit(OpCodes.Ldvirtftn, methodToBindTo);
            gen.Emit(OpCodes.Newobj, delegateCtor);
        }
    }
}